It is frequently desirable to add an additional axle assembly to a truck-tractor or trailer to increase the load carrying capacity of the vehicle. The maximum permissible load for each wheel of the truck is regulated by state law. If additional wheels are provided on the truck, the permissible truck load is increased thus permitting the trucker to haul a larger payload. In addition to complying with loading regulations, it is also desirable to add an extra axle when the load is to be increased in order to prevent undue wear on the vehicle.
The present invention provides an axle assembly which may be mounted on a truck to provide the desired additional axle. A novel lifting arrangement is provided to lift the axle off the ground when there is no load on the vehicle thus saving tire wear and engine fuel. The lifting structure is very compact in design so as to fit into the relatively small space which is frequently available for mounting the axle assembly.